First Law is the seventeenth episode of the fifth season. It was released on 6 March 2009.
When an AI kills the scientist who created her it opens a career door for Charlie, but first he and Amita must determine what happened. This involves putting her life in its hands, since Baley refuses to deal directly with Charlie, to whom she takes a dislike.
- The famous Three Laws of Robotics created by SF legend Isaac Asimov are the starting point here, particularly the First, which stipulates that no robot shall harm a human, or by their inaction allow a human to come to harm.